He said buen provecho, though I had no food

I had far too many bags for the cobblestone hill up to Guadalupe on Thursday evening. A man coming down turned around, took two of them without asking, and climbed with me, breathing exactly as hard as I was. At the top he handed them back, said, buen provecho, and went down again. I do not know why he said buen provecho. I had no food. I have carried a lighter bag since, in case I meet him, and I would like to give him something with food in it.